Neural Mechanisms Involved in Itch, “Itchy Skin,” and Tickle Sensations

Available evidence suggests that the sensation of itching is closely related to that of pain (1). Titchener (2) observed that when the skin was explored with a fine hair, well-defined points were found which gave rise to itching when the intensity of stimulation was low, and to pain on stronger stimulation. Bishop (3) found that itching resulted from repetitive low intensity electrical stimulation of pain spots in the skin. Lewis, Grant and Marvin (4) pointed out that noxious stimuli, if their intensity be decreased, can be made to produce itching instead of pain. Forster (5) and Bickford (6) reported that in patients who had